For Forum Owners
Simply drop this plugin's folder into your bbPress installation's my-plugins folder.
For Plugin Developers
For a plugin called My AWESOME plugin, insert the following into your plugin's header before the */:
Text Domain: my-awesome-plugin
Domain Path: /translations
(Of course, you'll need to change the text domain to fit your plugin.)
The text domain must match what you use when localizing, for example: __( 'Some words', 'my-awesome-plugin' ).
At the end of your plugin's main file, before the ?> if there is one, add the following code:
load_plugin_textdomain( 'my-awesome-plugin', dirname( __FILE__ ) . '/translations' );
Also, make sure that you follow the WordPress/bbPress internationalization guidelines.